The use of a laser beam to aid in the aiming of a firearm has gained considerable popularity in recent years. With the advent of rugged low power gas lasers, as well as solid state diode lasers, it is becoming increasingly possible and practical to attach a small laser to various types of firearms, including handguns. The theory of use is elegantly simple. When the firearm sighting laser is activated, a spot of light is formed on a target, providing an indication of the impact point of a firearm projectile. Even the most inexperienced firearm user can immediately hit an intended target with an extremely high degree of accuracy by simply pointing the firearm so that the laser spot rests on the target.
A firearm sighting laser may generate a spot of light that is either visible or non-visible to the human eye. For example, some types of conventional sighting lasers employ a helium-neon or solid state laser that generates a bright red beam highly visible to the human eye in appropriate lighting conditions. However, in some applications, such as military applications, it is preferred that the laser spot be visible to the firearm user alone. In these applications a laser is selected that cannot be seen by an unaided observer. Infrared wavelength lasers are an example of this specialized form of sighting laser. While perfectly visible to a user equipped with an infrared scope, the laser spot of the sighting laser is otherwise invisible.
Since the firearm projectile typically follows a generally flattened parabolic trajectory, while the laser beam propagates in an essentially straight line, the laser beam normally intersects the impact point of the projectile only within a prescribed range of preselected distances. If the range for use of the firearm is varied substantially, for example by selecting targets at 100 yards instead of 200 yards, the laser beam must be realigned to accurately intersect the changed impact point of the firearm projectile. To accommodate realignment of the laser beam, the light generating elements of the sighting laser are typically disposed within a housing that is rigidly mounted onto the firearm. Some form of alignment optics are then normally employed to orient the laser beam with respect to one or more points along the trajectory of the firearm projectile.
Unfortunately, most of the conventional apparatus employed for attaching a sighting laser to a firearm suffer from a number of drawbacks. The recoil associated with a firearm discharge normally subjects both the firearm and the sighting laser to relatively extreme shock and vibration. Further, even minute displacement of the sighting laser housing with respect to the firearm will cause substantial displacement of the laser spot with respect to the impact point of the firearm projectile. To overcome these extreme environmental conditions, conventional sighting laser mounting devices and sighting laser housings are commonly very bulky and still typically subject to misalignment, either with repeated discharge of the firearm or if the firearm is roughly handled. Military and law enforcement personnel, for example, do not always have the luxury of treating their firearms with the degree of gentleness often required by many conventional sighting lasers.
One conventional approach to mounting a sighting laser on a firearm involves the use of attachment devices developed for optical sighting aids, such as low power optical telescopes. These attachment devices, however, often obscure and render unusable the iron sights normally provided on the firearm itself. This circumstance is frequently considered unsatisfactory for many firearm applications, such as low enforcement and military applications. Other conventional sighting laser attachment devices attempt to mount the sighting laser underneath the barrel of the firearm by attaching the sighting laser to the trigger guard of the firearm. Unfortunately most trigger guard engaging arrangements cannot secure the trigger guard firmly enough to avoid rotation of the sighting laser with respect to the firearm after repeated discharge of the firearm in view of the associated recoil. The resultant rotation of the laser again typically misaligns the laser spot with respect to the firearm projectile impact point. Consequently, sighting lasers employing a mounting scheme that involves attachment to a firearm trigger guard typically require frequent realignment.
One successful sighting laser employing an underbarrel engagement of a firearm trigger guard is the model BA-2 sighting laser manufactured by Laser Devices, Inc., a California corporation. The model BA-2 sighting laser employs a clamshell type housing that includes opposing slots in a rearward portion of the laser housing that are configured to engage a substantial portion of the trigger guard. To achieve satisfactory rigidity in the alignment of the model BA-2 sighting laser with respect to the firearm, a substantial portion of the space bounded by the trigger guard, within which the firearm trigger is disposed, may be obscured. In some instances, for example where gloves are worn, this arrangement can interfere with satisfactory access to the firearm trigger. Thus there still exists a need for a compact and rugged firearm sighting laser that can be rigidly attached to a firearm trigger guard. The present invention fulfills this need.